A co-polarization-insensitive metamaterial absorber for 5G n78 mobile devices at 3.5 GHz to reduce the specific absorption rate

Specific absorption rate (SAR) by next-generation 5G mobile devices has become a burning question among engineers worldwide. 5G communication devices will be famous worldwide due to high-speed data transceiving, IoT-based mass applications, etc. Many antenna systems are being proposed for such mobile devices, but SAR is found at a higher rate that requires reduced for human health. This paper presents a metamaterial absorber (MMA) for SAR reduction from 5G n78 mobile devices at 3.5 GHz. The MMA is co-polarization insensitive at all possible incident angles to ensure absorption of unnecessary EM energies obeying the Poynting theorem for energy conservation and thus ensuring smooth communication by the devices. The unit cell size of the absorber is 0.114 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\lambda$$\end{document}λ making it design efficient for array implementation into mobile devices. This absorber has achieved a minimum of 33% reduction of SAR by applying to the 5G n78 mobile phone model, equivalent to SAR by GSM/LTE/UMTS band mobile phones and making it suitable for SAR reduction from next-generation 5G mobile devices.

Angle-insensitive co-polarized metamaterial absorber based on equivalent circuit analysis for dual band WiFi applications

A novel and systematic procedure to design a co-polarized electromagnetic metamaterial (MM) absorber with desired outputs and resonance frequencies for dual-band WiFi signal absorption is presented. The desired resonance frequencies with expected S parameters' values were first designed as an equivalent circuit with extensive analysis and then implemented into frequency-selective MM absorber by numerical simulation with precise LRC elements, satisfying least unit cell area (0.08λ), substrate thickness (0.01λ) and maximum effective medium ratio (12.49). The absorber was simulated for the maximum angle of incidence for both the normal and oblique incidences at co-polarization. The absorptions at the desired resonance frequencies were found at a satisfactory level by both simulation and practical measurement along with a single negative value to ensure metamaterial characteristics. The proposed equivalent circuit analysis approach can help researchers design and engineering co-polarization insensitive MM absorbers using conventional split-ring resonators, with perfection in output and desired resonance frequencies without the necessity of lumped elements or multilayer substrates. The proposed metamaterial can be utilized for SAR reduction, crowdsensing, and other WiFi-related practical applications.

Wide Bandwidth Angle- and Polarization-Insensitive Symmetric Metamaterial Absorber for X and Ku Band Applications

In this paper, a wide bandwidth angle- and polarization-insensitive symmetric metamaterial (MM) absorber for X and Ku band is proposed. For both normal and oblique incidence in TEM mode, the proposed unit cell shows high absorption at different polarizing angles due to structural symmetry. A four-fold resonator was introduced in the unit cell to enhance the bandwidth. The performance of the proposed absorber is determined by both full-wave simulations and measurements. The simulated and measured absorptions are almost similar at normal incidence with 94.63%, 95.58%, 97% and 75.58% at 11.31 GHz, 14.11 GHz, 14.23 GHz, and 17.79 GHz respectively. At 45° for these frequencies, the absorptions are 95.47%, 97.2%, 97.12% and 75.29% respectively. For 90°, the absorptions are similar to those for 45° except 98.15% for 14.21 GHz. At all these angles and resonance frequencies, either permittivity or permeability was found negative, as a result, the refractive index was negative revealing metamaterial characteristics of the unit cell. Along with high absorptivity and wide incidence angle insensitivity up to 90°, a total of 1.42 GHz of absorption bandwidth was achieved, which is better than recent similar works with FR4 substrate.

An analysis of the CFH Y402H genotype in AMD patients and controls from the UK, and response to PDT treatment

AIM

Mutation in the complement factor H (CFH) gene is an important risk factor for age-related macular degeneration (AMD). In this study, we identified the strength of the CFH Y402H gene variant association in a UK AMD cohort and tested the hypothesis that this variant may influence the biological response of choroidal neovascularisation (CNV) following photodynamic therapy (PDT) for CNV.

METHODS

A total of 557 cases with AMD and 551 normal controls were genotyped for the CFH Y402H (1277 C/T) variant using the 5' nuclease TaqMan assay for allelic discrimination. The CFH gene association for AMD, for the different CNV subtypes and for patients needing PDT was estimated. Twenty-seven PDT-treated patients were followed up for 15 months with ETDRS-derived vision, clinical examination, and fundus angiography. Individuals with different CFH genotypes were then analysed for any association with visual change following PDT.

RESULTS

The risk association for AMD with the CFH CC genotype (odd ratio (OR)=3.62, Pc<0.0001) was similar to that reported in other Caucasian cohorts. The magnitude and strength of this association was stronger in AREDS stages 2-4 (ORs=4.48, 2.69, and 5.17). ORs for the risk of predominantly classic CNV were significantly raised for both the CC (OR=17.87, P<0.0001) and CT (OR=9.06, P=0.0002) genotypes. The number of patients carrying the high-risk C allele was 70.4% in those requiring PDT as compared to 52.3% in the non-PDT group (OR=2.16, P=0.011), and presence of the CC genotype significantly increased the risk of PDT (OR=5.48, P=0.015). The degree of visual loss following PDT was significantly higher in the CFH CC genotype group (P=0.038); 50% of CC cases (n=13) and 45% of the CT cases (n=12) lost 15 or more ETDRS letters at final follow-up.

CONCLUSION

In this UK cohort of AMD patients, the CFH Y402H variant was significantly enriched in patients with predominantly classic CNV. Patients homozygous for the CFH Y402H genotype seem to have worse visual acuity after PDT.

Assessment of effect of nasal continuous positive pressure on laryngeal opening using fibre optic laryngoscopy

AIM

To assess the effect of nasal continuous positive airways pressure (CPAP) on the dimensions of the laryngeal opening.

METHODS

Nine preterm infants who had previously received ventilatory support for respiratory distress syndrome (RDS) were studied. All were receiving nasal CPAP. The laryngeal opening was visualised using a fibre optic video camera system. The ratio of width to length of the opening was measured on and off CPAP.

RESULTS

In eight of the infants the width: length ratio increased on CPAP; mean change for group +24.4% (95% CI +11.9 to +37.9).

CONCLUSIONS

Nasal CPAP seems to dilate the larynx. This may explain the selective beneficial effects of CPAP on mixed and obstructive apnoea.

Endocarditis in the 80s in a general hospital in Auckland, New Zealand

The clinical and investigative features of 102 episodes of infective endocarditis were analysed retrospectively. The most frequent presenting symptoms (malaise, fever, sweats, myalgia, weight loss) were non-specific. Fever, cardiac murmur, tachycardia, vascular phenomena and a change in mental state were the most common physical signs at admission. Anaemia was present in half the episodes and renal and liver dysfunction in about one-third. Streptococci (61) and staphylococci (31) were the causative organisms in all but 10 episodes. The commonest predisposing factors were underlying cardiac disease (52 per cent) and a preceding focus of infection (14.6 per cent). Left ventricular failure (33 per cent) and focal neurological disease (29 per cent) occurred frequently. Valvular surgery was performed in 20 episodes, with two in-hospital deaths. Overall hospital mortality was 27.5 per cent and death was most commonly neurological (11/28). A higher mortality was associated with elevated total white blood count, microscopic haematuria, renal or liver dysfunction at admission, S. aureus endocarditis, the development of left ventricular failure or focal neurological disease, age greater than or equal to 60 years and persistence of fever after one week of antibiotic therapy. The absence of both renal dysfunction at admission and subsequent microscopic haematuria identified a group with a very low hospital mortality (4.7 per cent). The three-year mortality of the entire group was 43.5 per cent.

Preventive treatment of asymptomatic left ventricular dysfunction following myocardial infarction

Progressive asymptomatic ventricular dilatation can occur following myocardial infarction and severe ventricular dysfunction is often present by the time clinical congestive heart failure occurs. In a randomized, double-blind trial, the effects of captopril 25 mg tid, frusemide 40 mg daily and placebo were studied in 90 patients with asymptomatic left ventricular dysfunction (ejection fraction less than 45%) 1 week following Q wave myocardial infarction. Left ventricular volumes and function were assessed at intervals during the subsequent year using two-dimensional echocardiography. The frusemide and placebo groups showed significant increases in ventricular volumes with stroke volume index unchanged and ejection fraction slightly reduced, whereas the captopril group showed a significant reduction in left ventricular end-systolic volume index with stroke volume index and ejection fraction increased. At 12 months the difference in the change in ejection fraction from baseline between the captopril and frusemide groups was 10.5% and captopril and placebo groups 9.6% (both P less than 0.0001). There was a significant difference in occurrence of clinical heart failure in the placebo group compared with the other groups (P less than 0.05). Blood pressure increased significantly within the normal range in the placebo and frusemide groups whereas there was essentially no change from baseline in the captopril group. There was no significant correlation between baseline left ventricular volumes and function and subsequent change, and anterior and inferior infarct subgroups showed similar responses within the treatment groups. In conclusion, captopril improves asymptomatic ventricular dysfunction and prevents clinical heart failure during the year following myocardial infarction. Frusemide may also prevent clinical heart failure but not progressive ventricular dilatation.

Effect of reducing atrial pressure on atrial natriuretic factor and vasoactive hormones in congestive heart failure secondary to ischemic and nonischemic dilated cardiomyopathy

The effect of an acute and sustained reduction in atrial pressure on atrial natriuretic factor (ANF) and vasoactive hormone secretion was studied in 9 patients with congestive heart failure (CHF). Intravenous nitroglycerin was titrated to reduce the pulmonary artery wedge pressure by 30 to 50% and maintain this reduction for 4 hours. After 60 minutes of nitroglycerin administration, the mean decrement in wedge pressure was 10.0 +/- 1.7 (standard error) mm Hg (35%) and plasma ANF was 65.3 +/- 13.9 pmol/liter (35%). The initial decrease, sustained reduction and later increase in plasma ANF levels closely paralleled the changes in pulmonary arterial wedge (r = 0.94, p less than 0.0001) and right atrial pressures (r = 0.91, p less than 0.0001) during and immediately after the nitroglycerin infusion. Plasma aldosterone and cortisol levels increased during the first 2 hours of the nitroglycerin infusion, but there was little change in plasma norepinephrine or plasma renin activity. Although levels were elevated in CHF, plasma ANF still responded rapidly to changes in atrial pressure. A sustained reduction in pressure produced a sustained reduction in ANF levels. These findings provide further support for a regulatory role of ANF, even in chronic CHF.

Treatment of patients with symptomless left ventricular dysfunction after myocardial infarction

In a randomised, double-blind trial 60 patients with left ventricular dysfunction (ejection fraction less than 45%) but without clinical evidence of heart failure 1 week after Q wave myocardial infarction were given captopril 25 mg thrice a day, frusemide 40 mg daily, or placebo. Left ventricular volumes were measured at baseline and at 1, 3, 6, 9, and 12 months with cross-sectional echocardiography and Simpson's rule analysis of standardised apical views. The captopril group showed no significant change in left ventricular end-diastolic volume index but left ventricular end-systolic volume index was significantly reduced and stroke volume index and ejection fraction were significantly increased from 1 month on. In contrast, the frusemide and placebo groups showed significant increases in ventricular volumes, with stroke volume index unchanged and ejection fraction slightly reduced. The changes in the captopril group were significantly different from those in the other groups.

Simple test of intestinal calcium absorption measured by stable strontium

A clinical test of intestinal calcium absorption has been developed using non-radioactive stable strontium as a calcium tracer. In nine elderly subjects there was a close correlation between the fractional absorption of strontium and radioactive calcium (45Ca) during a five hour period after the simultaneous oral administration of the two tracers. Comparable precision was achieved with each tracer in six subjects in whom the test was repeated after two weeks. The effect of food on strontium absorption was examined in a further 33 normal subjects (age 21-60 years), and the administration of the strontium with a standard breakfast was shown to reduce the variance at individual time points. A simplified test in which serum strontium concentration was measured four hours after the oral dose given with a standard breakfast was adopted as the routine procedure. The normal range (mean (2 SD], established over 97 tests in 53 patients, was 7.0-18.0% of the dose in the extracellular fluid. A further 30 patients with possible disorders of calcium absorption (10 with primary hyperparathyroidism and 20 with coeliac disease) were studied by this standard test. In both groups of patients the mean four hour strontium values were significantly different from normal. This standard strontium absorption test allows assessment of calcium absorption with sufficient sensitivity and precision to have a wide application in clinical practice.

Aspects of dermatology practice in Auckland

In June 1984, a survey of outpatient attendances at the Auckland Hospital skin clinic was carried out. Similar data was obtained about patients attending a dermatologist in private in Auckland. There were 869 visits to the skin clinic, 36% of them new patients, and 296 visits in the private clinic, 48% new. Twenty-eight percent of patients were over 65 years old. The most common conditions seen were cutaneous malignancies (20%), solar keratoses (17%), and eczema (17%).